1. Technical Field
The present invention relates to a construction of a bonding jig used in a process for manufacturing a head gimbal assembly (hereinafter referred to as an HG assembly), which is a component of a hard disk drive, and a method for separating the HG assembly from the bonding jig.
2. Description of the Related Art
FIG. 7 shows a construction of an essential part of a general HG assembly. FIG. 7A is a top plan view thereof, FIG. 7B is a front view thereof, and FIG. 7C is a perspective view of a tip end portion of the HG assembly.
As shown in these figures, an HG assembly 51 is made up of a load beam 52, a flexure 53, a slider 54, and mount plates 55. The mount plates 55 are formed along the upper and lower surfaces of a mounting portion 52a of the load beam 52, in which an attachment hole 56 for attaching the HG assembly 51 is formed, so as to hold the mounting portion 52a therebetween to reinforce the mounting portion 52a of the load beam 52.
In FIG. 7, the shape and dimension proportion of each element such as the slider 54 of the HG assembly 51 are shown by changing them from the actual ones for ease of understanding. A load portion 52b in a tapered shape of the load beam 52 has folded portions 52c and 52d formed by bending both edge portions of the load portion 52b at right angles, by which the rigidity of the load portion 52b is kept. A hinge portion 52e, at which the folded portions are not formed, is formed with an opening 52f to provide elasticity, and is bent at a predetermined bending angle α with a portion 52i indicated by the indicating line A passing through the opening 52f being a boundary. This bend is caused by plastic deformation, so that this angle α is kept in an unloaded state. However, FIG. 7A shows a state in which the hinge portion 52e is not bent to simplify the explanation.
The flexure 53 is configured so that a bonding portion 53a indicated by the hatching in FIG. 7A is bonded and fixed to the lower surface of the load beam 52, and an arch-shaped notch 53b is formed in the range from an unfixed intermediate portion to a tip end portion. A flexure tongue 53c formed by the arch-shaped notch 53b is formed with a pivot 53d projecting upward. At a stage at which the flexure 53 is fixed to the load beam 52, the tip end portion of the pivot 53d comes into contact with the lower part of the load beam 52 at one point, and other portions of the flexure 53 keep a state in which they are slightly separated from the load beam 52.
On the other hand, a pair of flexure arms 53f and 53g, which are formed by the arch-shaped notch 53b and are elongated in the lengthwise direction, act as springs at this time. Specifically, the flexure arms 53f and 53g are curved slightly so that the tip end portion of the pivot 53d is pressed on the lower part of the load beam 52 in order to keep this state. Therefore, the flexure tongue 53c is slightly turnable in all directions around the contact point of the pivot 53d while having a restoring force.
Also, the HG assembly 51 has an alignment hole 57 formed in the fixing portion 53a so that the center thereof is located on the centerline B connecting the center of the pivot 53d and the center of the attachment hole 56. To a bonding face on the lower surface of the flexure tongue 53c is bonded a bonding portion on an upper surface 54a of the slider 54 with a predetermined adhesive or the like as described below. Therefore, the aforementioned flexure arms 53f and 53g, the flexure tongue 53c, and the pivot 53d constitute a suspension portion of the HG assembly 51 for suspending the slider 54.
FIG. 8A is a top plan view of an essential part in the case where the flexure tongue 53c and the rectangular parallelepiped slider 54 are mounted to a bonding jig 61 to bond and fix these two elements to each other. FIG. 8B is a sectional view of the essential part, in which a cross section including the reference line C passing through the centers of an alignment pin 62 and an action pin 63 standing on an upper surface 70 of the bonding jig 61 is viewed in the direction of the arrow mark X.
When the slider 54 is bonded to the flexure tongue 53c, the slider 54 with a predetermined orientation is mounted on a slider mount 66. The configuration is such that a fixing lever 65 lies at the position indicated by the dotted line at this time not to hinder the work. At a stage at which the slider 54 has been mounted, the fixing lever 65 is moved in the direction of the arrow mark X and presses the slider 54 with a predetermined urging force to hold the slider 54 between the fixing lever 65 and an opposite side wall portion 67. Thereby, the slider 54 is held at a slider mounting portion formed by the slider mount 66, the side wall portion 67, and the fixing lever 65. The configuration is such that the upper surface 54a and a tip end surface 54c of the slider project from each of adjacent parallel surfaces of the bonding jig 61 through a predetermined width at this time.
On the other hand, when the HG assembly 51 to which the slider 54 has not been bonded is mounted to the bonding jig 61, the HG assembly 51 is mounted so that the alignment pin 62 of the bonding jig 61 is inserted in the alignment hole 57 in the HG assembly 51, and the action pin 63 of the bonding jig 61 is inserted in the attachment hole 56 in the HG assembly 51. The configuration is such that a clamper 64 is moved to a position at which the mounting operation is not hindered by a not illustrated means at this time.
Also, in the HG assembly 51, the center distance w1 between the alignment pin 62 and the action pin 63 standing on the bonding jig 61 is set so as to be substantially equal to the center distance between the alignment hole 57 and the attachment hole 56 in a state in which the bend at the angle α is stretched straight as shown in FIG. 7A. Therefore, at a stage at which the HG assembly 51 is mounted on the bonding jig 61, the HG assembly 51 is in a state of being stretched as shown in FIG. 8. In this state, the clamper 64 is moved to the position shown in FIG. 8, and the mount plate 55 of the HG assembly 51 is pressed on and fixed to the upper surface 70 of the bonding jig 61 with a predetermined pressing force.
Thereby, the upper surface 54a of the slider 54 and the lower surface of the flexure tongue 53c keep a state of being pressed on each other with a predetermined pressure. Therefore, an adhesive with low elasticity such as an epoxy adhesive is applied to either one bonding surface before these elements are joined, and this bonding state is kept during a subsequent predetermined drying process, by which these two elements can be bonded firmly or in a temporarily fixed state.
After the slider 54 is bonded to the flexure tongue 53c as described above, the HG assembly 51 is separated from the bonding jig 61. For this purpose, the fixing lever 65 pressing the slider 54 is moved again to the position indicated by the dotted line, and the clamper 64 is moved from the state shown in FIG. 8, that is, the state of pressing the mount plate 55 of the HG assembly 51, thereby releasing the HG assembly 51 from the pressed state. At this time, the HG assembly 51 tends to be restored to the state in which the bending angle β (FIGS. 9a and 9b) at the bending portion 52i becomes the aforementioned predetermined angle α.
Therefore, the engagement position of the alignment hole 57 in the HG assembly 51 and the alignment pin 62 fitting in the alignment hole 57 moves upward, and also the slider 54 tends to be inclined in the direction of the arrow mark W with two contact portions being the support lines. The two contact portions are a contact portion at which the lower surface of the slider 54 comes into contact with a corner 68 of the slider mount 66 and a contact portion at which a lower surface corner 54b of the slider 54 comes into contact with a slider mounting portion side wall 69 of the bonding jig 61.
However, the HG assembly 51 cannot move in the direction of the arrow mark Y due to the engagement of the alignment pin 62 with the alignment hole 57 in the HG assembly 51. Although the engagement position moves upward to some extent along with the deformation of the flexure arms 53f and 53g, the inclination of the slider 54 in the direction of the arrow mark W does not proceed due to the friction on the contact portions.
As described above, when the HG assembly 51 is separated from the bonding jig 61, the HG assembly 51 is caught by the bonding jig 61 during the separating process and a locked state is sometimes established. If an attempt is made to forcedly separate the HG assembly 51 from the bonding jig to release the HG assembly 51 from this state, there arises a problem in that the flexure is deformed plastically or the bonding portion of the slider is peeled off.